1. Field of the Invention
This invention relates generally to the field of liquid handling and storage and more particularly to a self-priming drain valve.
2. Description of the Related Art
A variety of storage systems have been devised to handle liquid loads and similar cargo. A typical storage system often includes a tank and may also include associated piping. The particular type of system and configuration will factor into the types of problems that the system may incur. Additionally, the type of liquid that the system handles also plays an important role in determining the possible difficulties users of the system may encounter.
There are many reasons for accessing a liquid handling system. If the system needs repairs, scheduled maintenance, or modifications, the system will often require being accessed in some manner. Many liquid systems include what are known as cut-off, or isolation valves. These valves perform the function their name implies, segregating the affected portion of the system to allow for the desired work to be done. However, even with the use of such valves, the system is often pressurized, or contains liquid within the section to be accessed. As a result, it is necessary to drain, or bleed off, some portion of the system prior to making repairs or performing maintenance activities.
Liquid handling system technology has evolved many methods of performing this function. Piping may often include small bleed off valves, or the system may include drain valves at certain points, including drain valves on a portion of a liquid holding tank. While extremely useful, these valves often experience problems themselves. For exampled, the liquid itself may include various amounts of particulate matter, which blocks the drain valves. The system itself may contribute rust and other solids to the liquid, or solid matter may precipitate out of the liquid and collect at various points within the system.
This sediment and particulate matter will tend to accumulate wherever there is a restriction of the flow within the system, such as a pipe bend. If the system is one wherein there is not a great deal of liquid flow, solid matter may accumulated at any point. Many systems incorporate filters and other screening systems in an attempt to purify the liquid.
All of the aforementioned problems may be illustrated in a variety of systems and different liquids. The problems can be found in residential applications as well as commercial. For example, the relatively simple residential water system experiences many of these problems. A prime exampled is a hot water tank.
Water heaters typically do not receive the appropriate maintenance for the simple reason that they have no moving parts and are often out of sight and mind. However, hot water tank performance is constantly being degraded by two things: sediment and rust.
Many steel hot water tanks include a glass liner to prevent rust. However, lining is not a foolproof solution, and the constant temperature fluctuations of the water within the tank cause the liner to expand and contract, resulting in tiny openings. When water eventually penetrates the lining, the tank will begin to rust. The rust then becomes deposited on the bottom of the hot water tank.
Simultaneously, the heating of the water causes calcium carbonate to form within it. As the calcium carbonate forms, it also settles to the bottom of the tank. In gas-heated water heaters, the sediment and rust eventually becomes thick enough at the bottom of the tank to reduce the heating efficiency. In electric tanks, sediment bonds to the heating element itself, forming a hard crust that may eventually render the element useless.
Draining of the hot water tank should be performed once a year to combat these problems. However, the average homeowner does not perform any maintenance on the hot water heater; rather replacement of a failed heater is often the alternative to yearly maintenance. Replacement of a hot water heater includes removal of the old tank. The only practical way of accomplishing this task is to drain the fifty gallons of a water that a typical tank holds.
This task becomes futile, however, if sediment and rust has built up upon the bottom of the tank, effectively blocking the drain valve. When the tank is in need of replacement, it is almost always the case that a layer of sediment and rust has built up above the point where the drain valve is located. There may exist other methods of penetrating the tank and utilizing a pump to drain the water, but this theory does not hot water tank filled with fifty gallons of water that can not be drained.
Unfortunately, the only recourse left to the repair personnel is to forcibly remove the installed drain valve. Damage to the water heater is not a concern, as the heater is being replaced in any event. What does happen, is that the fifty gallons of water in the tank will now come rushing out, with no means of containing it. If this scenario plays out in an unfinished basement, the only cost is the time it takes for the homeowner to clean up the mess with buckets and swabs. However, if the hot water heater is located in any other location, or the owner does not want some fifty gallons of water spilling out uncontrollably, some other solution is necessary. More particularly, in a multi-family home, or in any building where a hot water heater is installed somewhere other than a basement, such as an overhead, the owner will require the water to be drained in a controlled fashion.
The prior art does not provide a solution that adequately solves the problem. For exampled, the patent granted to Jenkins, U.S. Pat. No. 232,724, discloses a gage-cock that includes a rod for cleaning the internal portions of the device.
The patent granted to Fink, Jr., U.S. Pat. No. 743,702, discloses another gage-cock that includes a rod that is capable of being pushed forward and backward within the steam or water way for clearing obstructions. The rod is held in place when not in use via system pressure.
Murdock, U.S. Pat. No. 751,538 discloses a gage-cock assembly that includes a rod whose forward portion is threaded and terminates in a pointed end. When a separate hand wheel is turned, the threaded rod will travel forward until the pointed end projects into a boiler, thereby forcing out any obstructions.
Hinckley, U.S. Pat. No. 1,069,013 discloses a cleaning device for gage-cocks comprising a cleaning rod tipped with a scraper blade that is inserted into the bore of the valve. The blade may scrape the inside of the bore, as well as project through the mouth of the valve.
Olson, U.S. Pat. No. 1,467,492 discloses a device that combines a feed valve with a cleaner. The valve stem includes a flattened portion that cooperates with a slot in a cleaning head that will travel along with the valve stem as it is turned. The cleaning head may also be extended through the mouth of the valve. While these above-mentioned prior art patents disclose a general solution for removing obstructions in a valve or similar device, none disclose a solution amenable to the problems discussed above.
A prior art patent that comes closer to solving the problem is that granted to Watt, U.S. Pat. No. 5,964,243. Watt discloses a drain valve that includes a rod designed to pierce a layer of sediment that may have built up within a tank filled with fluid. The rod is connected to the opening means of the valve on one end, and includes a piercing tip on the other. The rod can turn along its axis and is designed to either move with the valve stem, or independently from it. The piercing tip may be made of a wear resistant element. When retracted the piercing tip is designed to provide a closing means for the valve, in that its diameter is closely related to that of the valve opening. The rod is moved along its axis by means of hydraulic pressure. Although this device is designed to pierce a layer of sediment, it is much more complicated than necessary of a hot water tank application. Additionally, the use of hydraulic pressure to actuate the valve mechanism results in an unworkable solution for a hot water tank application. Although the device disclosed in Watt may be suitable for its intended application, it does not solve the problems at hand.
Therefore, what is desired is a drain valve that is inexpensive to manufacture, and easy to install and use.
It is also desired that the drain valve include the option of either being permanently affixed to a tank, such as a hot water heater, or include means for removal such as threading.
It is also desired that the drain valve include means to overcome the problems associated with layers of sediment in rust that have accumulated on the bottom of the water heater.
Also desired is a method for draining water out of a tank in a controlled fashion so that the tank's contents may be captured.